Compensation method is for wavelength modulation spectroscopy and involves reference signal and masked signal received by detector stage with phase and amplitude output

摘要

The compensation method is for wavelength modulation spectroscopy and involves a reference signal and a masked signal received by a detector stage with phase and amplitude output. A first stage is involved where the reference signal is measured and stored, a second stage where the object signal is measured and a third stage where the object signal is compensated with the stored reference signal, so that an unmasked object signal is emitted. The object signal and reference signal are filtered by a filter before the third stage. The derivatives with regard to frequency and phase in the product of the filter and detector phase and amplitude output are mainly constant and further the derivatives with regard to frequency of the absolute value of the product of the filter and detector stage phase and amplitude output are mainly constant, so that the filter is compensated for the detector stage phase and amplitude output in such a manner that the object signal and reference signal original form is recovered.